A thin, `50.0 cm` long metal bar with mass `750 g` rests on, but is not attached to, two metal supports in a `0.950 T` magnetic field as shown in figure. A battery and a resistance `R = 25.0Omega` in series are connected to the supports.

(a) What is the largest voltage the battery can have without breaking the circuit at the supper
(b) The battery voltage has this maximum value calculated. Decreasing the resistance to `2.0 Omega` the initial acceleration of the bar.

Answer

A, B

Explanation

a. `ilB=mg`
or `V/RlB=mg` or `V=(mgR)/(lB)`
`=((0.75)(9.8)(25))/(0.5xx0.45)`
`=~~817V`
b. `a=(ilB-mg)/m=(VlB)/(mR)-g` (as `i=V/R`) ltbRgt `=((817)(0.5)(0.45))/((0075)(2.0))-9.8`
`~~112.8m//s^2`